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Police forces across the United Kingdom successfully lobbied to use a facial recognition system acknowledged as discriminatory against women, young people, and members of ethnic minority groups, after complaining that a less biased version generated fewer potential suspects.

The Technology in Practice

British police use the national police database to conduct searches using historical face recognition. This procedure involves matching a “probe image” of a person of interest against a repository of over 19 million custody photos to identify possible hits.

Acknowledged Discrimination

The Home Office conceded last week that the technology was biased. This admission followed a study by the government's National Physical Laboratory determined it misidentified people of Black and Asian heritage and females at much greater frequency than white men. The ministry stated it “had acted on the findings”.

“This raises the issue of whether facial recognition only becomes useful if users tolerate discrimination in race and sex. Convenience is a poor argument for disregarding basic freedoms.”

Long-Standing Problem

Internal documents show that this bias has been known about for more than a year. Furthermore, police forces lobbied to reverse an earlier ruling that was intended to mitigate the problem.

Senior officers were notified of the system's bias in late 2024. The government-ordered laboratory study concluded the system was had a higher probability to produce false positives for photos of women, Black people, and those under 40 years old.

A Policy U-Turn

In response, the National Police Chiefs’ Council (NPCC) mandated that the confidence threshold required for possible hits be raised to a point where the bias was significantly reduced.

However, this directive was overturned the following month following complaints from police that the modified technology was producing fewer “useful lines of inquiry”. NPCC documents indicate the stricter setting reduced the proportion of queries resulting in potential matches from 56% to a just 14%.

Profound Inequalities

Although the Home Office and NPCC refused to say what setting is now in operation, the recent independent review found the system could generate false positives for women of Black heritage almost 100 times more frequently than for white women at certain settings.

The ministry stated on these findings: “The testing found that in a limited set of circumstances the software is more likely to incorrectly include some demographic groups in its match reports.”

Balancing Utility and Fairness

Describing the effect of the temporary raise to the system's accuracy setting, the police records note: “This adjustment significantly reduces the effect of bias across legally safeguarded attributes of race, age and sex but had a significant negative impact on operational effectiveness”. The papers further note that police units complained that “a previously useful tool returned results of questionable value”.

Wider Implementation Proposals

Meanwhile, the government has launched a two-and-a-half-month public review on its plans to expand the use of biometric scanning systems. Policing minister the relevant minister has described the technology as the “most significant advance since DNA matching”.

Expert and Oversight Concerns

Abimbola Johnson, head of the advisory panel for the police race action plan, commented: “There was very little discussion through equality strategy sessions of the technology deployment even with obvious cross-over with the plan’s concerns.

“These revelations show yet again that the anti-racism commitments the police has undertaken through the race action plan are not being translated into wider practice. Our reports have warned that innovative tools are being implemented in a landscape where ethnic inequalities, inadequate oversight and faulty information gathering continue to exist.

“All deployment of facial recognition must meet rigorous official guidelines, be independently scrutinised, and demonstrate it reduces rather than compounds ethnic bias.”

Home Office Response

A Home Office spokesperson stated: “We treat the conclusions of the study seriously and we have already taken action. A new algorithm has been externally evaluated and procured, which has no statistically significant bias. It will be trialled early next year and will be subject to further assessment.

“Our priority is protecting the public. This gamechanging technology will support officers to apprehend and prosecute offenders. There is officer review in every step of the process and no arrest or charge would be taken without trained officers meticulously examining the output.”